/*
 * Copyright (c) 2014. Jordan Williams
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jordanwilliams.heftydb.util;

/**
 * A simple xor shift random number generator. Generates a predictable stream of pseudo-random numbers from a
 * starting seed.
 */
public class XORShiftRandom {

    private long last;

    public XORShiftRandom(long seed) {
        this.last = seed;
    }

    public int nextInt(int max) {
        last ^= (last << 21);
        last ^= (last >>> 35);
        last ^= (last << 4);
        int out = (int) last % max;
        return (out < 0) ? -out : out;
    }

    public int nextInt() {
        last ^= (last << 21);
        last ^= (last >>> 35);
        last ^= (last << 4);
        int out = (int) last;
        return (out < 0) ? -out : out;
    }
}
